the best place to confirm is with the consulate of Guatemala. However, I love this site offered by KLM
http://www.klm.com/travel/ch_en/travel_information/travel_planning/travel_clinic/visaform.htm, according to which provides this info for a Dominican citizen US LPR:
Visa required,
except for A max. stay of 90 days:
Additional Information:
- Admission and transit refused to deportees of non-Guatemalan
nationality.
- Visitors may be asked to provide proof of an onward/return
ticket.
- If required, the consul issuing the visa will advise
visitors For details, click here
- Visa exemption is for a max. stay of 90 days. However, one
extension is possible for another 90 days at the Immigration
Office.
Warning:
- Non-compliance with the entry or transit regulations will
result in deportation of passenger at carrier's expense and
fines of USD 1,000.- per passenger for transporting airline.